1. Field of the Invention
In accordance with a first particular aspect, the invention pertains to a motor vehicle drive train with a multi-clutch device, especially with a dual clutch device, installed between a drive unit and a transmission to transmit torque between the drive unit and the transmission, where the clutch device comprises a first clutch arrangement assigned to a first transmission input shaft and a second clutch arrangement assigned to a second transmission input shaft, where the transmission input shafts are essentially coaxial to an axis of rotation of the clutch device. A where an input side of the clutch device is connected either directly or indirectly by way of a torque-transmitting arrangement to a connecting end of a power takeoff shaft of the drive unit, and the torque-transmitting arrangement has a radially outer connecting area for the connection to the clutch device and a radially inner connection area for the direct or indirect connection to the connecting end.
2. Description of the Related Art
The main type of clutch in question here is a dual clutch device of the friction disk type, referred to in brief as a dual clutch, which has at least one clutch disk per clutch arrangement to serve as the clutch disk and an associated clamping plate, by means of which at least one friction area of the clutch disk can be pressed against an opposing support area, which can rotate in common with a housing arrangement of the clutch device. It is also quite conceivable, however, that the ideas of the invention presented below could also be applied to clutch designs of other types. The torque-transmitting arrangement can be an integral part of a clutch module which comprises the clutch device; that is, the torque-transmitting arrangement and the clutch module can constitute a single component which forms the clutch device, or the torque-transmitting arrangement can be a component or assembly separate from such a module, in which case it could be provided in the form of, for example, a flexplate.
Especially in the case of dual clutch systems with their-relatively complex pressure plate geometries, the clutch disks must usually be premounted between the pressure plate and the associated clamping plate. To connect the clutch device to the power takeoff shaft, a torque-transmitting arrangement in the form of a flexplate is frequently used, which is attached by several screws arranged around a reference circle to a connecting end of the power takeoff shaft or to a flywheel in cases where a flywheel (possibly a dual-mass flywheel) is attached to the power takeoff shaft first. If the clutch disks are already premounted in the clutch device, it is usually no longer possible in cases where the clutch device is already mounted on the drive unit to gain access to the screw holes located on the reference circle, which means that it is impossible to mount a preassembled unit comprising the flexplate and the clutch device itself, as a single structural unit, on the drive unit, that is, it is impossible to connect the clutch device, using the flexplate, either directly or indirectly, to the power takeoff shaft (possibly the crankshaft) of the drive unit. It is therefore necessary to mount the clutch device itself, which is possibly preassembled as a structural unit, and the flexplate independently of each other in such a way, for example, that the flexplate is connected to the power takeoff shaft first, and then the clutch device is attached to the flexplate, whereupon the drive unit can be connected to the transmission; alternatively, the flexplate is mounted on the drive unit, whereas the clutch device is attached to the transmission, and then the drive unit with the flexplate and the transmission with the clutch device are connected to each other. In any case, the clutch device unit on the one hand and the flexplate (i.e., the torque-transmitting arrangement in general) must be delivered as separate components to the assembly line of the motor vehicle producer, whereupon the assembly steps described above must be carried out. As a rule, the clutch module will be set onto the transmission input shafts first, and then the flexplate will be mounted on the power takeoff shaft (especially the crankshaft), whereupon the transmission and the drive unit (engine) will be connected, and finally the clutch module will be attached to the flexplate from the outside through at least one hole in the transmission housing shroud by means of, for example, at least three screws or the like distributed around the circumference. This assembly procedure is very complicated and also highly susceptible to error, because it is difficult to verify that the assembly work has been carried out properly, especially that the flexplate has been properly connected to the clutch device.
The object of the invention is to make it possible to install a preassembled installation unit comprising the clutch device itself and the torque-transmitting arrangement (possibly the flexplate or flexplate arrangement) into the drive train as a single unit without the need to separate the torque-transmitting arrangement from the clutch assembly afterwards. It would be especially ideal if this installation unit could also comprise the actuation unit belonging to the clutch device, so that the drive train would then consist in practical terms of only three components, namely, the drive train, the transmission, and the installation unit described above.
According to the invention, the torque-transmitting arrangement is connected nonrotatably under mediation of at least one positive connecting element, which nonrotatably connects the radially inner connecting area to the connecting end or to a component or assembly attached nonrotatably to the connecting end and which secures the radially inner connecting area to the connecting end or to the component or assembly in the axial direction, where the positive connecting element is located in a central radial area relative to the axis of rotation, which area is essentially equal to or smaller than the radial area occupied by the transmission input shafts.
Because the positive connecting element, such as a screw or a threaded bolt, is located in the central radial area or is installed there during the assembly procedure, it becomes possible to proceed in the axial direction to install the positive element in the central radial area. Once the positive connecting element has been installed, it can be accessed in its central radial area from the axial direction when necessary for the sake of maintenance or repair so that, for example, the clutch device or the above-cited installation unit can be replaced.
As a rule, it will be advisable for the radial area occupied by the radially inner transmission input shaft to comprise the central radial area.
If the clutch arrangements in question are clutch arrangements of the friction disk type, each of which has at least one clutch disk serving as a friction disk, which is mounted nonrotatably by its connecting hub to the assigned transmission input shaft, then it is preferred that, in a state corresponding to an open or as yet unassembled drive train where the transmission and the drive unit are separate from each other, the positive connecting element be accessible or installable through a central channel in the clutch device mounted on the drive unit. This central channel is defined by the receiving openings in the connecting hubs for the transmission input shafts assigned to them and possibly by a central opening in an actuating module, which is connected to the clutch device to form a single structural unit and which serves to actuate the clutch arrangements, this opening allowing the transmission input shafts to pass through in the axial direction.
The proposals according to the invention are not limited to motor vehicle drive trains with multi-clutch devices or dual clutch devices. Therefore, in accordance with a general aspect of the invention, a motor vehicle drive train is provided with a clutch device between a drive unit and a transmission to transmit torque between the drive unit and the transmission, which has at least one transmission input shaft, where the clutch device comprises at least one clutch arrangement assigned to a transmission input shaft. An input side of the clutch device is connected directly or indirectly by way of a torque-transmitting arrangement to a connecting end of a power takeoff element of the drive unit, and the torque-transmitting arrangement has a radially outer connecting area for connection to the clutch device and a radially inner connection area for the direct or indirect connection to the connecting end. The drive train is characterized in that the torque-transmitting arrangement is connected nonrotatably under mediation of at least one positive connecting element, which nonrotatably connects the radially inner connecting area to the connecting end or to a component or assembly attached nonrotatably to the connecting end and which secures the radially inner connecting area to the connecting end or to the component or assembly in the axial direction, where the positive connecting element is located in a central radial area relative to the axis of rotation, which area is essentially equal to or smaller than the radial area occupied by one of the minimum of one transmission input shafts. A radial area occupied by the transmission input shaft can comprise the central radial area. In the case of a clutch arrangement of the friction disk type, which has at least one clutch disk serving as a friction disk, which is mounted nonrotatably by a hub to its assigned transmission input shaft, it is preferred that, in a state corresponding to an open or as yet unassembled drive train where the transmission and the drive unit are separate from each other, the positive connecting element be accessible or installable through a central channel in the clutch device mounted on the drive unit, which channel is defined by a receiving opening in the connecting hub for the transmission input shaft assigned to it and possibly by a central opening in an actuating module, which is connected to the clutch device to form a single structural unit and which actuates the clutch arrangement, this opening allowing the transmission input shaft to pass through in the axial direction.
A positive connecting element which is located precisely in the center is preferred, such as a screw located exactly in the center. When the positive connecting element is in a radial area near the axis of rotation, it can be installed or accessed very easily in the axial direction.
It is not completely excluded that the minimum of one positive connecting element itself could establish the connection for rotation in common between the radially inner connecting area and the connecting end or a component or assembly attached nonrotatably to the connecting end. Nevertheless, it is preferred that the positive connecting element indirectly establish or secure the connection for rotation in common between the radially inner connecting area and the connecting end or a component or assembly attached nonrotatably to the connecting end, in that this positive connecting element holds or presses associated rotational driver formations or rotational driver areas against each other in mutual, rotationally driving engagement. For example, rotational driver formations can be provided which comprise serrations or at least one SAE gear set, preferably one without play. Another advantageous possibility is for the rotational driver formations to comprise at least one combination of a projection and a receptacle for the projection. For example, at least one mortise-and-tenon combination or a peg and hole combination could be used.
In addition to a positive connection (especially a positive central connection), however, it is also possible to consider a non-positive, frictional connection (especially a frictional central connection) of the clutch device to the connecting end or to the component or assembly attached to the connecting end. Thus, the positive connecting element can hold or press associated rotational driver areas in mutual frictional engagement for rotation in common. The rotational driver areas can be formed by essentially rotationally symmetric contact surfaces or can have essentially rotationally symmetric contact surfaces. It is preferable for the contact surfaces to be formed by the circumferential surfaces of a cone-conical hole combination, which is in a central location, especially in a location essentially coaxial to the axis of rotation.
In the case of motor vehicle clutches, axial impact and vibrational excitations as well as wobbling excitations emanating from the drive unit can cause problems. The flexplates usually used to connect the clutch device to the power takeoff shaft of the drive unit, especially to the crankshaft of an internal combustion engine, are unable to absorb or to equalize such wobbling movements sufficiently, nor are they able to absorb or to equalize axial vibrations sufficiently.
The applicant has the goal of providing dual clutches of the friction disk type in which an actuating module, serving to actuate the clutch arrangements, forms a single structural unit with the clutch device itself. The axial length of the clutch module will be a predetermined value. The axial space available in a drive train to accommodate the overall module consisting of this structural unit is also a preestablished design value. Even if all the components are within the prescribed manufacturing tolerances, it is therefore possible for an undesirable force-fit in the axial direction to occur when the overall module is installed in its the proper position in the drive train.
Against this background, it is proposed that the torque-transmitting arrangement for the motor vehicle drive train be designed with elasticity in the axial direction so that axial tolerances can be compensated and/or so that the clutch device can be disconnected from axial impact and/or vibrational excitations. It is also proposed that the torque-transmitting arrangement be designed with elasticity for the tipping/wobbling of the connecting end relative to a plane of the clutch device orthogonal to the axis of rotation, so that the clutch device can be disconnected from the tipping and/or wobbling of the connecting end. Because the proposed torque-transmitting arrangement makes it possible to compensate for axial tolerances, undesirable force-fitting can be avoided without the need to remain within very narrow tolerances with respect to the axial dimensions of the overall structural unit and of the axially adjacent drive unit (or of the axially adjacent transmission in the drive train), which define the axial space available. Because, in contrast to the rigid connection of the clutch device to the power takeoff shaft via the conventional flexplate, the proposed torque-transmitting arrangement ensures the appropriate disconnection of the components, essentially none of the excitations coming from the drive unit (axial and/or wobbling excitations) are transmitted to the clutch device.
It is also proposed for the motor vehicle drive train that the torque-transmitting arrangement have an axial elasticity and/or an elasticity with respect to the tipping/wobbling of the connecting end relative to a plane of the clutch device orthogonal to the axis of rotation such that a resonance frequency of the potentially vibrating system formed by the torque-transmitting arrangement and the clutch device with respect to axial vibrations and/or tipping/wobbling in the drive train is below a vibration excitation frequency corresponding to the no-load rotational speed. According to this proposal for further elaboration, it is ensured that the vibrating system is detuned with respect to the excitation frequency, especially important in practice, coming from the drive unit, so that, at least for this excitation frequency, a very effective disconnection is guaranteed between the drive unit and the clutch device.
For the drive train, it is also proposed that the torque-transmitting arrangement have a radially intermediate deformation area, which is designed with elastic resilience in the axial direction and which is designed with elastic resilience for the tipping/wobbling of the radially inner and radially outer connecting areas with respect to each other.
In accordance with this proposal for elaboration, a torque-transmitting arrangement of especially advantageous design is provided, which is especially effective at compensating for axial tolerances, i.e., which can equalize and disconnect axial excitations and/or tipping excitations.
It is also proposed by way of elaboration that the radially outer connecting area be formed by a ring-shaped section; that the radially inner connecting area be formed by a preferably plate-shaped central or hub section; and that the deformation area comprise at least one connecting section, which connects the ring-shaped section to the central hub area, preferably several connecting sections which connect the ring-shaped section to the central or hub area. What is intended here in particular is that the radially outer connecting area is formed by a ring-shaped part; that the radially inner connecting area should is by a preferably plate-shaped central or hub area; and that the deformation area comprises at least one connecting part, which connects the ring-shaped part to the central or hub part, preferably several connecting parts which connect the ring-shaped part to the central or hub part, where the ring-shaped part, the minimum of one connecting part, and the central or hub part are to be produced as separate parts, which are then connected to each other, preferably by riveting, to form the torque-transmitting arrangement.
The ring-shaped part and the central or hub part can be made inexpensively as sheet-metal parts. For the connecting parts, it has been found advantageous to design them in the form of strips. As an elaboration, it is proposed that the strip-like connecting parts extend in the circumferential direction over a certain circumferential angle. The connecting parts can be designed inexpensively as leaf springs or sheet-metal strips.
A design which offers a favorable axial softness or softness in the tipping direction and which is also advantageous in terms of production technology is characterized in that a middle area of the connecting part in question is connected to the central or hub part, whereas its two ends are connected to the ring-shaped part. The connecting parts can overlap each other axially to a certain extent. It is proposed in particular in this regard that the connecting parts, proceeding from the associated ends connected to the ring-shaped part, cross over each other in pairs somewhere in the intermediate area between these first ends and the other ends, i.e., the middle areas, which are connected to the central or hub part.
The torque-transmitting arrangement can be designed advantageously with a damping element arrangement to damp vibrations or vibrational excitations. For this purpose, it is proposed as being especially preferred that the damping element arrangement be integrated into the torque-transmitting arrangement between the radially outer connecting area and the radially inner connecting area, parallel to the deformation area, and that it exert a damping effect between the radially outer connecting area and the radially inner connecting area with respect to relative axial movements and/or relative tipping/wobbling. Another advantageous possibility is to integrate the damping element arrangement into the torque-transmitting arrangement between the radially outer connecting area and the deformation area and/or between the deformation area and the radially inner connecting area so that it can exert a damping effect between the radially outer connecting area and the deformation area and/or between the deformation area and the radially inner connecting area with respect to relative axial movements and/or relative tipping/wobbling.
The damping element arrangement can comprise a plurality of preferably viscoelastic, possibly strip-shaped, damping elements.
The invention also pertains to a clutch system for a drive train according to the invention, comprising a clutch device, possibly a dual clutch or multi-clutch arrangement, for the transmission of torque between the drive unit and a transmission, where the clutch device comprises at least one clutch arrangement assigned to a transmission input shaft, and where an input side of the clutch device is or can be connected either directly or indirectly by way of torque-transmitting arrangement to a connecting end of a power takeoff shaft of the drive unit. According to the invention, the torque-transmitting arrangement is designed in the same way as the torque-transmitting arrangement of the drive train according to the invention.
The invention also pertains to a torque-transmitting arrangement for the direct or indirect connection of a clutch device, possibly a dual clutch or multi-clutch arrangement, to the power takeoff shaft of a drive unit in a drive train according to the invention. According to the invention, the torque-transmitting arrangement is designed in the same way as the torque-transmitting arrangement of the drive train according to the invention.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.